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One of the nation’s largest perchlorate cleanups is using a green approach to restore a large swath of property in Southern California.

From 1934 to 1987, the Whittaker-Bermite Corporation manufactured, stored and tested explosives on 996 acres now considered to be prime real estate in the city of Santa Clarita, north of Los Angeles. The explosives included ammunition rounds, flares, detonators, signal cartridges and pyrophoric pellets (fragments that spark spontaneously) and ignitors.

Perchlorate, one of the primary ingredients in explosives, contaminated the soil and the local water supply wells. The chemical affects the ability of the thyroid gland to take up iodine which is needed to make hormones that regulate many body functions after they are released into the blood. Polycyclic aromatic hydrocarbons, volatile organic compounds and depleted uranium were also found on the property.

Working with the responsible party, Whittaker Corp. the DTSC project manager approved a cleanup approach that encouraged the growth of perchlorate-eating bacteria. Mixing the soil with acetic acid, which is essentially vinegar and water, the soil was placed in large bags that were sealed to keep out oxygen. The soil was amended with other nutrients, along with the acetic acid prior to placing it in the bags. After proving it to be a viable treatment method, the process was refined and made more efficient by placing the amended soil in treatment cells rather than bags. As the bacteria grew it needed energy, energy it received by breaking down the perchlorate. The process destroyed the perchlorate without leaving any toxic or harmful by-products. Each batch of soil took four to six weeks to process from excavation to destruction of the perchlorate. With the new technology in place all that was left in the soil after the perchlorate treatment was chloride, which is an innocuous naturally occurring compound. By utilizing this method of cleanup, there was no need to transport soil to an off-site landfill.

The treatment method is not new to DTSC, said Project Manager Jose Diaz, but hadn’t been used on a project with this amount of contaminated soil. The cleanup is considered one of the biggest perchlorate cleanups in the nation with about 394,000 cubic yards of soil on 226 acres. Accelerating the cleanup will allow the city to redevelop the property sooner. 

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